Rotary Cutter Slip clutch not slipping at factory specs...

[boggen]

been debating. spend a good half day to day tearing slip clutch apart and cleaning and putting it all back together. and hope nothing needs to be replaced / repaired. or spend 50 to 80 bucks and get a new slip clutch that fits between the pto shaft and pto on back of tractor. for this old "new idea" 452 bush hog. i recently got at an auction. it is going on behind a Allis chalmers CA. with 20hp at PTO.

everything on this thing is pure rust and no longer paint. but it is solid metal! i am almost guessing. the slip clutch is most likely rusted together, at least that is my fair guess.

 

[sweettractors]

Nice standard "company policy" answer, isn't it..

I'm willing to bet the setting protects their gearbox from overtorque from the tractor, but the tractor end of things (read expensive) is YOUR responsibility.

Largely, the days of a company willing to take a little time to look after their customers personal needs are gone.

Sean

Sometimes, I do things based on "common sense" way of thinking. Owners Manuals and authorized dealers advice take priority over what I personally feel. This keeps your mfgrs warranty in play and mfgrs liable for any damages that you may incur. Ken Sweet

 

[SPYDERLK]

been debating. spend a good half day to day tearing slip clutch apart and cleaning and putting it all back together. and hope nothing needs to be replaced / repaired. or spend 50 to 80 bucks and get a new slip clutch that fits between the pto shaft and pto on back of tractor. for this old "new idea" 452 bush hog. i recently got at an auction. it is going on behind a Allis chalmers CA. with 20hp at PTO.

everything on this thing is pure rust and no longer paint. but it is solid metal! i am almost guessing. the slip clutch is most likely rusted together, at least that is my fair guess.

Loosen it up and see if it will slip. If it does, tighten it a little and slip it for a few seconds. Thatll clean it up enuf. The let it cool and tighten it enuf so it will stall your tractor promptly when you drop the hog onto a rough brush pile. Cold clutch should warm just a little while stalling. At that setting it is not likely it will ever need attention if you can keep it dry and use it every few weeks. Make a habit of going back and feeling the clutch when you have hit something big, and/or stall. If it stays cold on a quick stall or some heavy hits its probably a little tight. If its hothot its too loose.
larry

 

[Travis_R]

I don't particularly care for this slip clutch stuff. I'm thinking about maybe selling the 285 and going back to a Squealer. I'd definately get the SQ160 shear pin.

What do you guys think?

 

[Chilly807]

I don't particularly care for this slip clutch stuff. I'm thinking about maybe selling the 285 and going back to a Squealer. I'd definately get the SQ160 shear pin.

What do you guys think?

There's days I agree with you, mostly when it's been sitting outside for a few weeks and I'm not sure it'll slip as advertised. My experience with shear bolts has been that they work all the time, every time, but at the same torque level regardless of tractor.

I know some folks curse them because they break them all the time, and to be honest, they aren't perfect.

How can a 3/8 grade 2 bolt protect both an 80 horsepower tractor and a 25 horsepower tractor equally well and still get the most performance out of the cutter and gearbox? It can't.

The slip clutch is tune-able to either tractor with a bit of common sense, which is rarely common anymore. I used to think (up til this thread) that the factory setting was "good enough". After some careful thought, mine's been tweaked and works fine that way.

Gotta like TBN, if only for the breadth of opinion and experience.

Sean

 

[Haywire]

While you're at it, sell that thing you're typing on and get yourself a good ol' Smith-Corona typewriter. They're absolutely immune to viruses and won't ever get hacked.

 

[SPYDERLK]

While you're at it, sell that thing you're typing on and get yourself a good ol' Smith-Corona typewriter. They're absolutely immune to viruses and won't ever get hacked.

... Its a matter of what you are getting for little or no extra trouble. With both it is a lot. The mystique and intimidation with slip clutches follows from the adjustment feature and how much the friction can vary if neglected - and no easy way to know what you actually have. The shear bolt is simple and stable with time and neglect. ... But the very fact that a gearbox survives with a shearbolt tells you it can survive very high overloads momentarily. -- And the nuisance shearing gives rise to the reports of replacing the bolt with Gr5 or Gr8, or even drilling out sloppy holes [due to too much shearing] and going up a size. Where are the broken gearboxes? So maybe the torque at which gearboxes sustain damage is so high that even that "stuck" clutch will slip. When you are dealing with reasonable tractor/implement power matches there is a large range of safe clutch slip torque. Going high enuf in this range will give the "set it and forget it" option if the implement sees fairly regular use. Its not so hard to find this operating area by marking the clutch and using it. Pretty soon youll hit a cinder block or stump. The clutch should slip incrementally for a momentary such hit .. or several revolutions if something gets caught and the engine stalls. The clutch will get hot in the latter. For me this is an optimum clutch operating point because the tractor will not overpower the clutch and burn it before you notice the implement is not at speed. -- With tractor/implement over or under matches different system defensive stategies apply. For a little tractor you loosen the clutch a bit to spare the tractor. You can use the same incremental slip/stall type of test. Same thing for a larger tractor, but only up to a point. A tractor of more than double the rating of the implement gearbox can be a serious danger. Somewhere up there you get into a range where you cant stall the engine without a clutch setting that would damage the gearbox. When your implement is not capable of sustaining the torque necessary to bog the engine you ar robbed of a critical cue to overload. I would tread carefully here. The clutch must exhibit some incremental slippage in impact conditions but should run without significant heat. If it runs hot it is slipping too often and you need to lighten the load and tighten the clutch slightly.
larry

 

[North Country]

My experience with shear bolts has been that they work all the time, every time, but at the same torque level regardless of tractor.


Sean

My experience is not the same. When the bolt is through two plates perpendicular to the rotational shaft (common on PTO shafts, image 1), I haven't seen one fail - although I'm sure someone else has. When the bolt is through two concentric shafts (common on snowblower augers, image 2) I've seen the shafts rust together to the point that not enough stress is transferred to the shear pin and an expensive auger gets bent badly. A dent or bend in the shaft can also cause the bolt to not fail. You have to take them apart and check them every now and them, just like a slip clutch.

Sure they always break at the same torque regardless of the tractor - but sometimes they're protecting the equipment (which has a specific failure point) as much as they're protecting the tractor.

 

[captflx]

I don't think the Bush Hog answer is wrong. The primary function of the slip clutch is to protect the gearbox and driveline. Assuming the slipclutch is working correctly, it will slip when over torqued. If the clutch is set correctly, is not "frozen" and is stalling tractor, that means that the cutter is being loaded more than the tractor h.p. available for what is being cut. You can slow down, raise the cutter, or alter the clutch to slip early. In the case of the latter, you will quicky or prematurly burn the clutch. If not inspected on a regular basis, more than the clutch pads will be damaged. By the way, the proper way to check a clutch is to loosen the springs, mark all components with a black marker pen and engage tractor PTO. If all parts are loose, no marks should align. If any two marks do, disassemble, clean off rust, reassemble, and readjust springs.

 

[Travis_R]

I don't think the Bush Hog answer is wrong. The primary function of the slip clutch is to protect the gearbox and driveline. Assuming the slipclutch is working correctly, it will slip when over torqued. If the clutch is set correctly, is not "frozen" and is stalling tractor, that means that the cutter is being loaded more than the tractor h.p. available for what is being cut. You can slow down, raise the cutter, or alter the clutch to slip early. In the case of the latter, you will quicky or prematurly burn the clutch. If not inspected on a regular basis, more than the clutch pads will be damaged. By the way, the proper way to check a clutch is to loosen the springs, mark all components with a black marker pen and engage tractor PTO. If all parts are loose, no marks should align. If any two marks do, disassemble, clean off rust, reassemble, and readjust springs.

The slip clutch... nothing but a hassle!